Orbital abrading tools are well-known and generally comprise a portable, manually manipulatable housing, a motor supported by the housing and having or being coupled to a drive shaft driven for rotation about a first axis, and an assembly for mounting a pad for abrading or polishing a work surface for orbital movement about the first axis. In a random orbital abrading tool, the assembly serves to additionally mount the pad for free rotational movement about a second axis, which is disposed parallel to the first axis.
The assembly typically includes a head portion coupled for driven rotation with the drive shaft about the first axis and defining a mounting recess having an axis arranged coincident with the second axis, a bearing supported within the mounting recess, and means for connecting the pad to the bearing for rotation about the second axis.
Locking mechanisms for orbital abrading tools are known in the art and described in U.S. Pat. No. 6,749,493 (Wuensch); U.S. Pat. No. 6,974,370 (Hutchins); U.S. Pat. No. 6,485,360 (Hutchins); and, U.S. Pat. No. 5,823,862 (Heidelberger. The locking mechanisms are also known as spindle-locks in the art.
U.S. Pat. No. 6,749,493 (Wuensch) discloses a spindle-lock using a circumferential slider to engage at least one pin to lock the mechanism. By moving the slider circumferentially, a spring retained pin will be forced to vertically engage a hole in a gear wheel, locking the spindle. Wuensch shows a one-piece design for both the motor assembly and the head assembly. Thus, a new tool would be necessary for use with a different head assembly (such as a non-orbital head or a grinder wheel). Furthermore, the circumferential slider comprises many components, increasing the cost of manufacturing and overall weight of the tool.
The same deficiency is present in both U.S. Pat. No. 6,485,360 (Hutchins), and U.S. Pat. No. 5,823,862 (Heidelberger). Although they have different forms of locking mechanisms, the locking mechanism, head assembly, and rotatable means about a second axis are permanently affixed to the abrading tool housing. This broad incorporation restricts the capabilities of the tool. Thus, a new tool would be necessary for use with a different head assembly (such as a non-orbital head or a grinder wheel).
U.S. Pat. No. 6,974,370 (Hutchins '370) presents a similar deficiency. Hutchins '370 shows a spindle lock for an orbital abrading or polishing tool. The head assembly is removable from the abrading tool, but the locking mechanism and means for orbital motion are structural components of the abrading tool housing. Thus, a new tool would still be necessary for a non-orbital head or a grinder wheel.
Furthermore, the locking mechanisms, or spindle-locks, described in the references above can be awkward to manipulate by a user wearing work gloves. Also, the locking mechanisms can be engaged accidentally by the user while the tool is in operation, resulting in excessive wear of the locking mechanism components and reducing the lifetime of the rotary tool and its components.
What is needed then is a locking random orbital dual-action head assembly wherein the rotatable means about an orbital axis and locking mechanism are structural components of the head assembly so that the head assembly can be used with a standard rotary tool. Thus, a single rotary tool can be used and different head assemblies can be attached for various uses. Also, costs can be reduced as individual head assemblies or rotary tools can be repaired or replaced independent of an entire head-assembly/rotary tool combination as in the prior art.
What is also needed is a head assembly comprising a locking mechanism that can not easily be accidentally locked while the tool is in operation, reducing unnecessary wear on the head assembly's or rotary tool's components.